As the technology for dynamically setting up a communication path in a communication network, the Multiprotocol Label Switching (MPLS) (IETF RFC3031 standard by E. Rosen et al.) architecture, and the Generalized Multiprotocol Label Switching (GMPLS) (IETF RFC3945 standard by E. Mannie) architecture are adoptable. The technology is to set up a label switched path (LSP), which is a virtual communication path, in a communication network, which includes TDM switches, time-division multiplexers, packet switches, and other network devices, according to a signaling protocol such as the Generalized Multiprotocol Label Switching (GMPLS) Signaling Resource Reservation Protocol-Traffic Engineering (RSVP-TE) Extensions (GMPLS RSVP-TE) (IETF RFC3473 standard by L. Berger).
A technology described in patent document 1 (JP-A-2005-252385) or a technology described in non-patent document 1 (R. Bradford et al., “Preserving Topology Confidentiality in Inter-Domain Path Computation and Signaling,” IETF Internet draft, draft-bradford-pce-path-key-00.txt, 2006 Jun. 16) is known as a method for establishing a communication path over layers or management domains through signaling in a case where a GMPLS network or any other network includes multiple layers or multiple management domains.
According to the technology described in the patent document 1, when a communication path is established according to the RSVP-TE, a link (that is, a communication path in a lower-level layer) to be employed in a communication path can be determined for each service that utilizes the communication path. Specifically, a service identifier is assigned in advance to the communication path in the lower-level layer, and an edge node in an upper-level layer issues a communication path establishment request with the service identifier appended to the request. A node on the border between the layers selects a link, of which the service identifier squares with the service identifier contained in the received communication path establishment request, from among selectable links.
The technology described in the non-patent document 1 provides a means that when a communication path is established using the GMPLS between a node within a first management domain (hereinafter, domain 1) and a node within a second management domain (hereinafter, domain 2), a route to be followed by the communication path is determined through collaboration processing among management entities called path computation elements (PCEs) that manage respective domains.
To be more specific, when a source node requests the PCE in the domain 1 (hereinafter, PCE 1) to perform route calculation, the PCE 1 calculates the route of a communication path for an interval in the domain 1 (hereinafter, interval 1), and requests the PCE 2 to perform calculation of the route of a communication path for an interval in the domain 2 (hereinafter, interval 2). The PCE 2 returns key information (path key), which represents the result of the calculation for the interval 2, to the PCE 1. The PCE 1 returns the route for the interval 1 and the path key for the interval 2 to the source node.
The source node issues a communication path establishment request that contains the path for the interval 1 and the path key for the interval 2. A border node between the domain 1 and domain 2 uses the received path key to query the PCE 2, and thus acquires the route for the interval 2 so as to establish the communication path for the interval 2.